Practical Control for Two-Mass Positioning Systems in Presence of Saturation

 The precision positioning systems generally need a good controller to achieve a fast response, high accuracy and robustness. In addition, ease, simplicity of controller design structure and high motion control performance are very important for practical applications. For satisfying these requirements, nominal characteristic trajectory (NCT) with proportional integral (PI) and notch filter (NF) as a compensator has been proposed as a practical control method for two-mass rotary PTP positioning systems. However, the effect of the actuator saturation cannot be completely compensated due to integrator windup when the object parameter varies. This paper presents a method to further improve nominal characteristic trajectory following (NCTF) controller to overcome the problem of integrator windup by adopting PI anti-windup schemes. The improved NCTF controller is evaluated experimentally using two-mass rotary positioning systems. The effect of the design parameters on the robustness of the improved NCTF with anti-windup integrator controller is evaluated and compared with NCTF without anti-windup integrator and the equivalent PID controller. The results show that the improved NCTF controller is effective to compensate the effect of integrator windup

Natural logarithm-based sliding mode control for two DOF active engine mounting system

The needs of powerful engine and lighter car body has adverse effect to the vibration occurred in the car. Obviously the presence of the engine vibration will imposed to the discomfort of the driver and passengers as well. To isolate the vibration, active engine mounting (AEM) has been proposed as the new generation of engine mounting. The control method becomes key factor of successfulness of AEM system. This paper presents a control method using natural logarithm-based sliding mode control (ln-SMC) for two degree-of-freedom (DOF) active engine mounting system. The performance of the controller is evaluated by applying sinusoidal and random disturbance to the system. Robustness of the proposed controller can be evaluated by increasing magnitude of the disturbance. The result shows that proposed control method not only able to attenuate the vibration of the different types of disturbance but also robust for magnitude variation of disturbance

Enhance ride comfort and road handling on active suspension system by PSO-based state-feedback controller

Determine the state feedback controller gain in the LQR controller is quite challenging as it requires multiple attempts of trial and error process. To eliminate the trial and error method when selecting the optimal controller parameter, we propose a PSO-based state feedback controller for the active suspension system. It is an intelligent-based method to determine state feedback gain controller by employing optimization technique using Particle Swarm Optimization (PSO). Unlike optimization-based LQR controller which seek the optimum Q and R matrices and then calculate the LQR feedback gain, in this study, the PSO algorithm is used to determine feedback gain controller parameters directly. In addition to the simple and straightforward controller design approach, the proposed controller is designed to obtain the optimum state feedback gain for improving both ride comfort and road handling aspects simultaneously by employing a multi-objective optimization technique. The proposed controller is applied on a quarter-car active suspension model. The controller performance is evaluated using Performance Index value based on the response of the suspension system under different road excitation, i.e. bump road profile and sinusoidal road profile at the frequency range from 1 to 10 Hz. The simulation results showed that the proposed controller improves both ride comfort and road handling successfully

Natural logarithm sliding mode control (ln-SMC) using EMRAN for active engine mounting system

Robustness of the controller becomes major important factor in active engine mounting system to ensure the vibration of the engine can be attenuated in entire range of operating speed. As robustness is the main advantage of sliding mode control, it has been proposed for vibration control applications. However, most of the proposed sliding mode control are using linear sliding surface. In addition, there is no schematic method to determine the optimum sliding function. In this paper, natural logarithm-based sliding function is introduced. By its nature, natural logarithm function is nonlinear function. Since it consists of one parameter only, which is related to maximum allowable vibration level, it is more easily to be determined by the designer. Moreover, the advantage of fast on-line training using Extended Minimum Resource Allocating Network (EMRAN) algorithm, made it possible to design feedback control law without having to obtain the precise system model which is normally becomes major difficulties of sliding mode approach

Terminal sliding mode control for active engine mounting system

This paper discusses terminal sliding mode control for active engine mounting (AEM) system to isolate vehicle engine body vibration. The engine vibration may occur due to road irregularities, at low frequency, and also reciprocating mechanism of the piston in the engine, at high frequency about 20 – 40 Hz. Active engine mounting system is designed to deal with isolation of vibration in high level frequency. A number of controllers for AEM system have been proposed. One of them is sliding mode control. However, there is no systematic method to determine sliding surface for conventional sliding mode technique to assure the system will be asymptotically stable. The main advantage of the proposed controller compared to the conventional (linear) sliding mode control is that the sliding motion to the origin (stable condition) can be reached in finite time by introducing the nonlinear sliding surface based on the concept of terminal attractors. The result shows that terminal sliding mode control not only able to attenuate the vibration but also robust to the different type of disturbance and parametric uncertainties such as mass, stiffness, and damping coefficient